TWI409532B - Contains a regular arrangement of controllable light modulating elements An optical modulation method, and an optical modulation device for a total image reproduction apparatus - Google Patents

Abstract

In known light modulation means, complex phase and amplitude values for modulating light waves are implemented and modulated either separately by two different light modulation means or a light modulation means having two layers of double-refracting materials, leading to increased expenses for material and adjustment. A new device is disclosed that simplifies the modulation of light waves in phase and amplitude in a single light modulation means made of double-refracting material. In a device having regularly disposed, controllable light-modulated elements having a double-refracting material for complex modulation of coherent light waves, and a modulation controller controlling the force-induced alignment of the optical axes of the molecules of the double-refracting material, means are provided for independently aligning the optical axes of the molecules in the light-modulating elements in two dimensions. The alignment can take place by electrical, magnetic, or optical acting means.

Description

a device containing a regularly arranged array of controllable light modulation elements Setting, light modulation method, and light modulation device for holographic reproducing device

The present invention relates to a light modulation device comprising a regularly arranged controllable light modulation element, the device having a birefringent molecular material for phase and amplitude modulation of a coherent light wave, the molecular axis of which is controlled by a force applied The effect is modulated.

The application object of the invention is a light modulation device, such as a planar spatial light modulation device with high image resolution, which is specifically used in video recorders, televisions, projectors or other similar appliances for holographic reconstruction. In combination with an illumination element and optical system, the device can be used as a holographic reconstruction of a scene hologram. The display can act as a direct view or projection display. As for the controllable element, it is a pixel in a light modulation device.

The present invention relates to instant or near real-time holographic display of an image. The image in this paper is composed of many scenes (individual images) and is encoded as an hologram in the elements of the optical modulation device. Different conventional methods used in encoding take into account the characteristics of the optical modulation device.

The term _" regular arrangement controllable element" in the description of the present invention includes both the meaning of the pixel of the optical modulation device, and also indicates a coding region in the optical modulation device that continues to be unpixelized, and the pre-display is performed through the region. The information is configured into discrete blocks.

The particular style of a holographic display as mentioned in the applicant's prior patent documents, such as (1) EP 1 563 346 A2, (2) DE 10 2004 063 838 A1 or DE 10 2005 023 743 A1, is well known. In these files, the calculation of the hologram is performed on the following basis: a three-dimensional scene is scattered into many object points during encoding and holographic reconstruction, so that each object point of the scene can be reconstructed again, in coherent light. The amplitude and phase of the light are changed by the controllable elements as they pass through the light modulation device.

For example, a single object point is encoded within an individual block of the optical modulation device coding region, which is responsible for reconstructing the object point and is referred to as a sub-hologram of the object point. The sub-image is almost equivalent to the 全 effect of holographic coding, reconstructing an object point at its focus, and encoding the object point in the form of complex values. The total number of complex values, that is, the amplitude value remains unchanged after amplification through the sub-image, and the amplitude height depends on the axial distance from the object point to the screen and the intensity of the object point. The phase distribution of the complex value in the sub-image range is almost equivalent to the effect of a lens, and the focal length depends on the distance from the object point to the optical modulation device or the axis of the screen. The value of the object in the light modulation device recorded outside the sub-image is 0, that is, the pixels of the light modulation device only work on the reconstruction of the single object point in the sub-image, the whole The image is generated by superimposing individual sub-images.

For example, holographic reconstruction of the scene may occur in a reconstruction zone that interacts with an optical reconstruction between the visible range and the light modulation device. From light The wavefront obtained from the holographic image of the encoded image in the device is superimposed in the visible range, and the object point reconstructed in the range can be seen by the position of the viewer's eye.

The viewer's eyes cannot see the reconstruction of the superimposed and modulated wavefront at the same time. From the perspective of each eye of the viewer, in time or space multiplex, the scene will produce three-dimensional perspectives due to parallax differences. Presented, but viewed by the brain is a single omni-directional three-dimensional display.

As for the reconstruction of the three-dimensional scene, the viewer can look at a light modulation device in which the hologram of a scene is directly encoded and used as a screen. This method is called direct vision construction. Or the viewer looks at a screen, an image or a holographic value that is encoded and converted in the light modulation device is projected onto the screen. This method is called projection construction. In addition, the position of the viewer's eyes will be derived in a generally well known manner from a positioner that is programmed to interface with the operator.

The hologram of the scene can also be generated by a computer, and the holographic value is stored in a memory unit as a lookup table, and the complex value of each object point is marked in the operator as a calculation result of a scene hologram. The complex value shall be written or encoded into the optical modulation device. If in a pixelated spatial light modulation device, the complex value will be encoded in the pixels of a spatial light modulation device (SLM), if not in a In a pixelated optical modulation device, the complex value is encoded in an ongoing coding region that is regularly subdivided into discrete blocks by pre-displayed information.

To modulate the resulting coherent light waves, conventional optical modulation devices simply perform phase modulation of the light wave or cause amplitude modulation. In addition, there are also optical modulation devices that perform both amplitude and phase modulation, combined with a fixed amplitude and phase value (but not any complex value) into these modulation devices.

Traditionally, a method for solving complex-valued representations on a light-modulating device has been to use a number of adjacent pixels in a light-modulating device to represent a complex value, but this approach has historically had its drawbacks.

For example, amplitude encoding on several adjacent pixels typically results in reduced diffraction efficiency of the light modulation device. Usually, the encoding of the phase values on several adjacent pixels requires an extra time to perform a complicated iterative process, so that the pre-encoded values can be as close as possible to the real scene.

Other methods well known to solve complex-valued representations (e.g., US 5 416 618) employ a combination of several optical modulation devices, such as two phase modulation devices or one phase and one amplitude modulation device. The disadvantage is that there is a rather cumbersome calibration process in order to perform a consistent calibration of the two light modulation devices of the pixel grating.

The optical modulation device described in the patent document US Pat. No. 5,719,650 is used to independently control the amplitude and phase. The modulation device is composed of two polarization rotating elements disposed between two carrier substrates and a respective liquid crystal layer, and each liquid crystal layer is further provided with a ground electrode and a grid electrode. Mutual calibration of these elements will be performed during the manufacturing phase Row. However, currently only liquid crystal light modulation devices can provide complex value data directly written to a holographic scene and modulate the light.

A specific implementation of a light modulation device is based on the use of a well-known liquid crystal layer (LC). The liquid crystal is a birefringent molecular material, for example, the direction of the molecules can be aligned in a desired direction by a magnetic field, thereby aligning the direction of the molecular optical axis, wherein the optical axis of a nematic liquid crystal corresponds to the longitudinal axis of a molecule. The modulation of the incident light in this type of optical modulation device depends on the alignment direction of the molecules (relative to the direction through the optical modulation device) and the polarization of the light.

Generally, the conventional liquid crystal light modulation device selects not the amplitude modulation device or the phase modulation device.

What is described in EP 0 583 114 is an optically addressed spatial light modulation device (OASLM) which has a light guiding layer in addition to the liquid crystal layer and the electrodes. With the writing light applied to the light modulation device, the light conductivity of the light guiding layer changes depending on the intensity of the writing light. If an electric field is applied to the electrodes and the photoconductive layer, the photoconductive layer will have an effect on the field adjacent to the liquid crystal layer due to the alignment of the optical transmittance by the written light. Calibration of the molecules of the liquid crystal layer is performed by an electric field and is used to modulate sufficient coherent readout light.

Relative to the electric field-positioned optical modulation device (EASLM), each pixel must have an individual control voltage addressed, while the optically addressed spatial optical modulation device (OASLM) has a fixed control voltage and a localized portion of the molecule. Modulation is performed by writing light.

In a modulation device with a single liquid crystal layer, the phase and amplitude cannot be modulated in a mutually independent manner, since there is usually only one calibration using an electric field generated on the liquid crystal layer or a similar force. The parameters are changing to affect the direction of the molecular axis of the liquid crystal. Next, the phase modulation will be described in Fig. 1, and the amplitude modulation will be further explained in Fig. 2.

In the first figure, a pixilated phase modulation device of the prior art is shown in a diagram, and its function will be explained later by using a pixel P-sized modulation device section, but only for some important components. description.

The pixel P is represented by a frame containing a birefringent molecular material such as a liquid crystal layer LC and a molecule M, and the coherent light is projected almost on the liquid crystal layer. Since the direction of light incidence is perpendicular to the plane of the drawing, a cross is added in the middle of a circle in the figure.

From the top view of Fig. 1a, the molecule M at the exit position in the closed state of the phase modulation device can be seen. The incident light is vertically polarized and can be seen with a double arrow, while the direction of the molecule M is aligned parallel to the incident light for calibration.

Figures 1b and 1c show the pixel P in the on state of the phase modulation device at medium voltage. The direction of the molecule M is located at an angle to the plane through the applied voltage V. If the applied voltage is at its maximum, the optical axis can be vertically aligned with this plane. According to Fig. 1c, the liquid crystal layer is surrounded by two face-to-face parallel carrier substrates TS such as a glass substrate, and the molecules M pass through the two face-to-face electrodes of E1 and E2. The generated electric field is used to optically control the direction of the molecules. The direction of incidence of light is indicated by an arrow, and the direction of polarization of the light does not change due to the applied voltage V, but the phase of the light is affected by the alignment of the optical axis of the molecule M.

According to the current technology, there are similar situations in the amplitude modulation device, for example, on an IPS (In-plane switching) display, the effect of which is in the form of a cross section in Fig. 2 according to the pixel size. To explain. As shown in Figures 2a and 2b, similar to Figure 1, is a top view of pixel P, and Figure 2c is a side view. In the state shown in Fig. 2a, the direction of the molecular optical axis and the polarization of the incident light in the closed state are the same as those in Fig. 1a. However, the arrangement of the two electrodes E1 and E2 in Fig. 2a is different. In this case, the applied voltage V acts from left to right, but no electric field is seen in the side view, since this figure is only a rough schematic. Moreover, since the side expansion of the pixel is usually larger than a few micrometers, the lateral electrode is generally divided again so that no excessive voltage is applied. So there are several electrodes connected in series for each pixel, but for the sake of clarity, only two electrodes are drawn here.

The pixels P in the on state are shown in Figs. 2b and 2c. The molecular and molecular M optical axes in the plane of the second plane are rotated by the application of the voltage V, and it can be seen from a slight tilt of the molecules M. Conversely, the molecular axis of the upper view plane in Figure 2c does not rotate.

The polarization of the incident light is shifted from the polarization direction PO1 to the position of PO2 at a specific angle under the condition that the applied voltage V is aligned with the optical axis of the molecule M and the thickness of the liquid crystal layer LC is set. The magnitude of the rotation angle is equivalent to twice the angle between the polarization direction PO of the incident light and the optical axis calibration of the molecule M. In addition, the amplitude of the light can be modulated by the polarizing mirror not shown here after the light passes through the liquid crystal layer. For example, the maximum amplitude obtained by using a parallel polarizer without applying a voltage, but the amplitude obtained when the applied voltage, the molecular twist of 45°, and the polarization of 90° are zero.

In summary, it can be determined that if a single optical modulation device is used, it is only possible to modulate the incident light wave with a partial complex value.

As for the combination of two liquid crystal light modulation devices in a manufacturing stage in order to simultaneously perform amplitude and phase modulation, it is necessary to pay attention to certain specifications. Since the two light modulation devices require a glass substrate or a flexible carrier substrate in addition to the liquid crystal layer, a large distance is also formed between the two liquid crystal layers.

For a correct complex-valued modulation, the pixels of the two light-modulating devices must be parallel and pass the light through the corresponding two pixels. However, since the distance between the liquid crystal layers is inevitable, such a condition cannot be fulfilled for a small angle of the incident beam, especially if the light is tilted through the optical modulation device. Even if the light is incident vertically, it may cause light to pass through each of the two different light-modulating devices due to the inaccurate alignment of a light source originally belonging to two pixels, and this disadvantage is particularly suitable for those suitable for those. The holographic reconstruction is only a few micrometers of small side pixel size, so I want to use A combination of two light modulation devices to make a holographic scene reconstruction is difficult to achieve.

SUMMARY OF THE INVENTION It is an object of the present invention to avoid the disadvantages of the prior art holographic complex value representation and to simplify the phase and amplitude calibration of light waves in a single optical modulation device.

The present invention is directed to a device having regularly arranged and controllable light modulation elements having a controllable layer of birefringent molecular material and a polarizer disposed at the output for coherent light waves The phase and amplitude are modulated, and the calibration of the molecular optical axis by force is controlled by a modulation controller to control the calibration of the optical axis of the birefringent material on the optical modulation element.

The object of the present invention can be achieved by providing an adjustable medium that can two-dimensionally calibrate molecules of a birefringent material on a light modulating element, wherein the calibration of the molecules can be adjusted independently of the other dimension in one dimension. . According to a preferred embodiment, the birefringent molecular material consists of a single liquid crystal layer.

According to the features of the present invention, the molecular optical axis can be calibrated by two adjustable media that are caused by external influences. Thereby, the influence on the molecular optical axis can be progressively controlled, and the angles of the two optical axis projections of the birefringent molecular material are aligned on two mutually perpendicular planes.

Various independent combinations of amplitude and phase can be represented by different complex values through independent two-dimensional calibration of the optical axis. Different from the current technology, in a light modulation device designed according to the invention, the calibration values of the amplitude and phase of the light wave are no longer fixed or must be coupled to each other.

At least one medium caused by external influences in the first embodiment of the medium is an electric field.

At least one medium caused by external influences in the second embodiment of the medium is a magnetic field.

At least one of the molecular axes of the third embodiment of the medium is calibrated with an optical medium.

Another feature of the invention is that two media that generate an electric or magnetic field are arranged approximately vertically on the light modulation elements of the light modulation device.

For calibration with optical media, there are two suggested solutions: In the first solution, the liquid crystal layer or other birefringent molecular material layer is doped with dye molecules, and the writing light is applied to the modulation device. Polar variations are calibrated on one plane, while calibration on the other plane is accomplished by the generation of an electric or magnetic field. In the second scheme, the molecules are calibrated on a plane by the intensity variation of the incident written light. For this purpose, the device must also contain a photoconductive material to react to the writing light, and an electric field or magnetic field can be generated in another plane. Any other combination of this embodiment is also possible.

In other embodiments of the invention, the apparatus is a spatial light modulation device comprising a light modulation element. If a scene hologram is written into these elements and the device additionally contains a lighting unit and optical system, the device can be applied to the reproduction of the hologram scene. Such devices can be used as light modulation devices in holographic displays.

Another main feature of the present invention is that the light modulation element is a pixel, and in order to perform modulation on two planes, the medium for modulation is arranged in pairs to the pixel so that the incident light is simultaneously phased and amplituded by pixel. Modulation.

Furthermore, the object of the present invention can be achieved by a method of modulating amplitude and phase of sufficient coherent light waves with a device having regularly arranged and controllable light modulation elements, wherein the device has a birefringent molecule a controllable layer of material, and a polarizer disposed at the output end, wherein the calibration of the optical axis by the force of the molecular axis is controlled by a modulation controller, thereby controlling the calibration of the optical axis of the birefringent material, The adjustable medium performs two-dimensional calibration of the molecules of the birefringent material on the light modulation element, wherein the calibration of the molecules can be adjusted independently of the other dimension in one dimension.

The numerator will be calibrated in the method step by two media that are subject to external influences and can be adjusted independently of each other. In particular, the calibration of the molecules must be constantly adjusted.

In one embodiment of the method, an hologram of a scene is written into a device implemented by the optical modulation device. If a lighting unit takes a picture of the hologram Shot, the lighting unit can be used together with an optical system to reconstruct the holographic image of the scene. These combined components enable a holographic reproduction device to be implemented.

In another embodiment of the method, two electric fields, which are generated by the conductive elements and are perpendicular to each other and which are independent of each other in intensity, act on the molecular optical axis to enable phase and simultaneous injection of the incident light. Modulation in amplitude.

The transformation of the above method can be performed by two magnetic fields that are perpendicular to each other and that can be adjusted independently of one another, which act on the molecular optical axis and modify its calibration. Similarly, an optical field and a magnetic field perpendicular thereto can be combined to calibrate the molecular optical axis. It is also feasible to calibrate the molecular optical axis with other media combinations mentioned in the device patent request.

The molecular optical axis in the plane of the light modulation device can also be optically calibrated, for example, by photoalignment with polarized writing light, calibrated in a birefringent molecular material doped with dye molecules, and Calibration is performed by an electric or magnetic field on another plane perpendicular thereto. If the device already contains illumination elements of at least one linearly polarized light source, the polarization of the light source can be substituted for the polarizing plate disposed on the light incident surface. In this case, the polarization of the write light can be varied without the influence of interference due to the relationship of the polarizer. Another method of using polarized write light is to use a light modulation device that produces a reflection of the wavelength of the read light.

The holographic reconstruction of a holographic reproducing device can be achieved using the optical modulation methods and media described herein.

The holographic reproducing apparatus has an illumination unit and a light modulation device having a light modulator having regularly arranged pixels and a liquid crystal layer, the molecules of the liquid crystal layer and the optical axis of the liquid crystal layer In order to be able to modulate the phase and amplitude of sufficient coherent light waves of an illumination unit, two-dimensional calibration is performed through an adjustable medium that affects the pixels by external influences, wherein one dimension can be adjusted independently of the other dimension. Molecular calibration, wherein the tunable medium acting on the pixel is formed in a manner as set forth in any one of claims 1 to 13 to enable the final phase value of the holographically encoded 3D scene and The amplitude values are simultaneously modulated, wherein the holographic reproducing device further includes an optical system for reconstructing the three-dimensional scene within a reconstruction range by the light waves modulated in the optical modulator.

With the apparatus of the present invention, it is possible to calculate the encoding of the complex image of the three-dimensional scene hologram and the adjustment of the coherent light by the phase and amplitude values to simplify, since only a single spatial light modulation device and a single liquid crystal layer are required. Conversely, what the prior art uses is not to combine several optical modulation devices, that is, one optical modulation device consists of several liquid crystal layers. Another advantage is that the method of solving with a plurality of optical modulation devices, the light diffusion between the single liquid crystal layer and the carrier layer can avoid the influence of interference.

The invention will be described in an embodiment of a tonal tone modulator. The light modulation device is specifically designed to penetrate or reflect in the pixelated coding region. Implemented, and consists of regularly arranged pixels and their limited expansion, pixels are separated by intervals depending on the manufacturing situation. As for the liquid crystal modulation device, the coding region passes through a thin electrode grid, and the pixel and pixel pitch are located between the electrode grids. The electrode switch allows the pixel to be amplitude and phase encoded in a transmissive or reflective mode via a control unit, in particular a computer with a built-in programming tool. Transmissive pixels encoded with complex values allow the incoming light waves to pass through, while reflective pixels reflect light waves. For the sake of clarity, the description of optical or other electronic electrical media will be omitted.

The invention is based on the consideration that since the birefringent molecular material consists of a molecule and two optical axes acting on two different planes, it is suitable for the complex value display used to modulate the incident light. In order to influence the phase and amplitude of the light waves in a mutually independent manner, the molecular optical axes must be independently two-dimensionally calibrated. The following is the basic concept: If a slice is placed on a birefringent molecular material and a coordinate axis is placed on the slice, the geometric projection of the optical axis at that slice will form an angle with the coordinate axis. This angle may vary due to the oscillation of the molecular optical axis in this plane.

If the second slice is perpendicular to the first slice and the axis of the second slice is perpendicular to the first coordinate axis, the geometric projection of the optical axis also forms an angle with the coordinate axis. According to the invention, changing the two angles independently is equivalent to independently performing a two-dimensional calibration of the molecular optical axis.

The alignment of the optical axis is generally combined with the polarization of the incident light. For example, in order to rotate the molecular optical axis two-dimensionally on the pixel of the light modulation device of a birefringent molecular material, Place a polarizer in front of the light modulation device. If a linear polarized light source is used for the illumination, the polarization of the light source occurs exactly at the position of the polarizer.

If only the direction of the molecular optical axis on a plane is observed from the top view, it is conceivable that the linearly polarized incident light is decomposed into one component and parallel to the molecular optical axis, and the other component is perpendicular to the optical axis. When light passes through a birefringent molecular material such as a liquid crystal layer, an optical path difference between the two components due to the refractive index of the liquid crystal layer parallel and perpendicular to the optical axis is formed.

This optical path difference depends on the thickness of the liquid crystal layer penetrating on the one hand and the rotation of the planar liquid crystal molecules on the other hand. The light component that is initially perpendicular to the optical axis is still vertical, while the other component parallel to the optical axis changes its angle with the molecular optical axis due to the rotation of the molecule. Therefore, another effective refractive index of light is also produced. As for the thickness of the liquid crystal layer, the optical path difference of the two components is smaller.

In general, light passes through the liquid crystal layer to form an elliptically polarized light, but after passing through the liquid crystal layer, the polarizing mirror passes only partially to become linearly polarized, and produces a predetermined phase A and phase retardation δ. In general, the optical path difference of one wavelength λ is equal to 2 π divided by the phase delay δ. According to the formula, the phase delay depends on the birefringence Δn and the thickness of the liquid crystal layer: δ=2 π/λΔn d

According to the formula, Δn depends on the rotation angle of the molecular axis perpendicular to the plane:

Wherein, the refractive index n _{= is} parallel to the molecular optical axis, and n _{⊥ is} perpendicular to the molecular optical axis. This parameter is characterized by the use of birefringent molecular materials and is therefore a parameter specifically used for this material.

As for δ, the sign of the optical phase retardation is determined from the plane depending on the thickness of the liquid crystal layer and the angle of the molecular optical axis, and θ is the rotation angle sign of the molecular optical axis with respect to the direction of the polarization of the light before entering the liquid crystal layer. In addition, in the case where the two polarizers are parallel, the light passes through the liquid crystal layer and the second polarizer to obtain the following formulas of amplitude and phase:

amplitude:

Phase:

If the thickness of the liquid crystal layer is adjusted so that the optical axis rotates and at least one phase shift of 2 π can be obtained from the plane in a general phase modulation device whose amplitude cannot be changed, the rotation of the liquid crystal molecules on the plane can be transmitted, that is, The combination of different amplitude and phase values is adjusted by the change in angle θ.

In the above two formulas, the variation of the special case θ = 0 and δ is equivalent to a phase modulation at a constant amplitude, and the variation of the special case δ = π and δ is equivalent to an amplitude modulation. The change of the two parameters θ and δ allows the complex value modulation of the light.

In general, polarized mirrors can be configured in other ways, and thus other different amplitude and phase equations can be derived.

The optical axis of the molecule can be calibrated using different media caused by external influences in the light modulation device on the basis of light modulation. Further explanation will be given in the following embodiments.

Figures 3 through 5 are only illustrative of several important parts of the apparatus of the present invention.

In particular, in a transmissive optical modulation device including a single liquid crystal layer, modulation control is performed on a single pixel, wherein one pixel P contains at least two electrodes E1, and E2 can functionally control the molecule M. Similarly, the optical axis of the liquid crystal layer LC molecule M is also calibrated in pixels. If this method is not suitable, an additional indication must be given.

In the first embodiment of the invention, a medium that generates an electric field is used to perform pixel calibration of the molecular optical axis.

Figure 3a shows a transmissive optical modulation device in the form of a pixel P in the closed state. Shown in the upper view is a liquid crystal layer LC molecule M in a plane interposed between two mutually perpendicularly acting electrodes E1 and E2 to functionally control the molecule M. In addition, the vertical polarization of the incident light in the pixel P is indicated by a double arrow. The optical axis calibration, vertical polarization, and incident direction of the coherent light of the molecule M are consistent with the type of light modulation device described in the prior art. For comparison with molecular calibration on two different planes, Figures 3b and 3c show a side view 1 and a side view 2 of the molecule M in pixel P in a closed case. The arrow marks the light shot The direction of entry. The prior art shown in Figures 1 and 2 contains only a side view, and a side view of Fig. 2 rotated 90 degrees is added to make the description clearer.

Figures 3d to 3f show a pixel P in an on state according to the first embodiment. The electrodes E1 and E2, which are controlled by the modulation controller in parallel with each other and in a mutually independent manner, generate two electric fields to calibrate the molecules. By the application of the voltage, the optical axis of the molecule M in the pixel P is calibrated in a plane range by the rotation angle θ (see Fig. 3d), and the rotation angle ψ is obtained in the other plane. It can be seen from the above formula that the rotation angles θ and ψ affect not only the amplitude of the incident light but also the phase. Fig. 3e is a side view of Fig. 1 showing the molecular optical axis rotation angle θ due to the application of a voltage, which acts on the other plane.

Figure 3f shows a side view of Fig. 2 rotated 90 degrees from Fig. 3e with one pixel and four voltage values V0, Va, Vb and Va + Vb. The voltage of the lower left electrode is V0, and the voltage of the upper left electrode is Vb. Since the voltage Va-V0 can be placed between the left and right sides, the voltage Vb-V0 can be placed between the upper and lower sides, so the voltage value of the upper right electrode is Va+Vb, and therefore, the change of the voltage value Va+Vb can be The two-dimensional (upper and side) calibration of the molecular optical axes in the pixel P is independently performed, and the amplitude and phase of the passing light are modulated by the optical axis alignment. Since the voltage values are set independently of each other, there can be different combinations of amplitude and phase values. Similar to Figure 2, this figure is also a sketch. The electrodes in Figures 3a and 3d can also be replaced with a plurality of electrodes in series on the pixel to allow the pixels to be expanded in different lateral and thickness directions.

Furthermore, in a second embodiment of the medium, not further illustrated, a magnetic field that is perpendicular to the pixel can be fabricated to replace the two electric fields generated by the different voltages. The configuration of the medium can be similar to that of electric field fabrication in order to independently align the molecular optical axes in two planes. Alternatively, an electric field can be combined with a magnetic field perpendicular thereto on the pixels of a light modulation device.

Optical media or methods can also be used to calibrate the molecular optical axis in other embodiments.

The first implementation method used in optical media is optical alignment, in which a molecule is optically calibrated on a display plane in a light modulation device of a birefringent molecular material, that is, a liquid crystal layer is doped with dye molecules. The molecular optical axis is calibrated after the incident light is polarized. Such optical modulation devices are well known as so-called doped-dyed optical spatial modulation devices (dye-doped OASLM). This write light incident by a light source can be an incoherent light source. The molecular optical axis is calibrated by an electric field generated by a conventional electrode on a plane perpendicular to the display plane. Optical modulation devices of this type are well known as electric field addressed spatial light modulation devices (EASLM).

Figure 4a shows a combined example of an OASLM and an EASLM modulation device as a cross section of a pixel P in the upper view. The molecules in the liquid crystal layer LC and their micro-rotation can be seen from the plane. These molecules are vertically aligned with the direction of polarization (POS) of the written light. The incident light used here to influence the molecular calibration in the liquid crystal layer LC is referred to as write light, and conversely, the read light is light modulated by the light modulation device. The example here is one The polarization direction POL of the vertical polarization is marked by a double arrow other than the pixel P. However, the polarization of the polarized light may also differ depending on its other characteristics and the wavelength of the read light. It is not necessary to install a polarizing mirror on the injection plane of the optical modulation device.

The side view shown in Figure 4b is a molecular calibration of another plane perpendicular to Figure 4a, which is generated by an electric field. Compared to the plane of Figure 4a, the numerator is rotated more by the modulation controller through the complex value shown here. At the same time, the structure of the electrode, the electrical location of the light modulation, and the configuration of the carrier substrate are illustrated by the pixel P and conform to a conventional liquid crystal light modulation device. The direction of incidence of the readout light is indicated by a dashed arrow. In general, the combination of optical and electric field addressing allows independent two-dimensional calibration of a molecular optical axis.

Another type of OASLM is to establish an electric field through optical control and writing light. Another electric field perpendicular to this can be independently calibrated in the OASLM by means of TFT (thin film transistor) and electronic control. This will be explained in more detail in the following: In a second embodiment of the optical medium, the light modulation device incorporates a light guiding layer in addition to the liquid crystal layer. In Fig. 5a, a side view of a pixel P including a molecule M of the liquid crystal layer LC, an electrode E1/E2, a carrier substrate TS, and a photoconductive layer PS is used as a section of a light modulation device. In addition, it can be seen that the molecules are located at the exit. This figure also shows the writing process in the pixel P, and the discontinuous arrow indicates the direction in which the writing light is projected on the photoconductive layer PS.

As for the light conductivity of the photoconductive layer PS, it will vary depending on the intensity of the writeable light.

For the readout process of the read light, a fixed external voltage _Vfest is applied, and the adjustment of the effective voltage _Veff on the liquid crystal layer depends on the light conductivity of the photoconductive layer PS, and the light transmittance is transmitted through the write light. Make adjustments. The calibration of the molecular M optical axis is performed on this plane based on the effective voltage, and the side view of Fig. 5b is illustrated in Fig. 1 .

The operation is the same as that of the general OASLM modulation device, and the polarization direction PO of the readout light is also indicated by double arrows. Just as in an IPS (Plane Conversion) spatial light modulation device, electronically control it on a plane perpendicular to it, and convert a plane's in-plane voltage value for the pixel P of each optical modulation device. Addressing, for which an electric field is generated in pixel P.

Figure 5c shows the electrical addressing at another angle in a side view rotated 90 degrees from Figure 5b. Through the lower electrode and its voltage values V0 and Va and the voltage above and its voltage values V _fest and Va+V _fest , there is an external voltage difference fixed from bottom to top near the pixel P, wherein the effective voltage above the liquid crystal layer will be written The light is independently optically adjusted, but from left to right there is a voltage that is electrically addressed in the vicinity of each pixel of a light modulation device in a manner independent of each other. Through this combination, the molecular axes can be independently calibrated in two planes.

Addressing two independent voltage values for each pixel in the horizontal and vertical directions in this control compared to electrical control alone, using a combination of electrical and optical control in the pixels of a light modulation device Molecular independent calibration has the advantage of being less expensive in electronic display technology.

The diagram in Fig. 6 is a combination of amplitude and phase values as a complex value modulation of the incident light on a light modulation device, wherein the horizontal axis table has a relative amplitude from 0 to 1, and the vertical axis table has a phase from 0 to 2 π. The dots in the figure represent different complex values and their respective amplitudes and phases, and the amplitude and phase can be adjusted by different parameters θ and δ.

The invention can be used on pixilated and unpixelated light modulation devices. If the calibration of the molecular axis requires at least one medium to generate an electric field, it must be a pixelated light modulation device combined with electrical and optical calibration.

If the numerator is calibrated on two axes with an optical medium, an unpixelated light modulation device can also be used, that is, an external pixel structure is regularly displayed on the modulating device through pre-displayed information. . For example, an arrangement of two writing beams can be used, wherein one beam undergoes molecular calibration in one plane through the intensity variation of the writing light, and the other beam is calibrated in another plane through polarization.

In a holographic reproducing apparatus comprising a light modulation device, an hologram of a three dimensional scene is encoded, wherein the modulating device comprises a liquid crystal layer and is designed according to one embodiment described, simultaneously by a lighting unit and A light source that is nearly coherent illuminates the light modulation device. Another modulation controller modulates the incident light through the corresponding calibration of the molecules of the liquid crystal layer, and independently performs amplitude and phase modulation on two different planes, and combines an optical system to make the scene with the modulated light wave in a reconstructed Rebuild within scope.

The optical modulation device designed according to the present invention can not only make the complex value modulation of amplitude and phase in different combinations only need to be performed in a single optical modulation device, and apply it to a holographic scene reproduction. The holographic display can also greatly reduce the cost of materials (only one optical modulation device is required) and the cumbersome operation.

The technology disclosed in this case can be implemented by a person familiar with the technology, and its unprecedented practice is also patentable, and the application for patent is filed according to law. However, the above embodiments are not sufficient to cover the scope of patents to be protected in this case. Therefore, the scope of the patent application is attached.

LC‧‧‧Liquid layer

PO‧‧‧polar direction

P‧‧ ‧ pixels

M‧‧‧ molecules

TS‧‧‧bearing substrate

E1, E2‧‧‧ electrodes

V0, Va, Vb, Va+Vb, V _fest , V _eff ‧‧‧ voltage

θ, Φ‧‧·rotation angle

POS‧‧‧polar direction

POL‧‧‧polar direction

The optical modulation device and corresponding methods will be further described below in accordance with the invention. The figure illustrates the following: Figure 1a is a top view of a light modulation device pixel and liquid crystal layer molecules for phase modulation in a closed state; Figure 1b is a light modulation device pixel and liquid crystal layer for phase modulation. a top view of the molecule in the open state; a side view of Fig. 1c Fig. 1b; Fig. 2a is a top view of the pixel and liquid crystal layer molecules of a light modulation device for amplitude modulation in a closed state; Figure 2b is a top view of a light modulation device pixel and liquid crystal layer molecules in an open state for amplitude modulation; a side view of Fig. 2c and Fig. 2b; and a light modulation device pixel of the present invention The upper view of the liquid crystal layer molecules in the closed state; the side view of Fig. 3b, Fig. 3a; the side view of Fig. 3c and Fig. 3b, which are rotated by 90 degrees; the pixel of Fig. 3d, the light modulation device And a view of the liquid crystal layer molecules in an open state; a side view of Fig. 3e, Fig. 3d, a side view; Fig. 3f and Fig. 3e, a side view of a 90 degree rotation; Fig. 4a a top view of the optical modulation device pixel and liquid crystal layer molecules; a side view of FIG. 4b, FIG. 4a; a fifth side view of the pixel of the present invention with optically calibrated molecules during writing; Figure 5b is a side view of the readout process during optical calibration in Figure 1; Fig. 5c and Fig. 5b are side views of Fig. 2 rotated at 90 degrees; Fig. 6 is a graph of amplitude and phase modulation as a complex value modulation of the present invention.

E1, E2‧‧‧ electrodes

V‧‧‧ voltage

TS‧‧‧bearing substrate

LC‧‧‧Liquid layer

M‧‧‧ molecules

POL‧‧‧polar direction

Claims (26)

A device comprising a regularly arranged controllable light modulation element having a controllable layer of birefringent molecular material and a polarizer disposed at the output for amplitude and summation of sufficient coherent light waves Modulation in phase, wherein the modulation of the optical axis of the birefringent material on the light modulation element can be controlled by a modulation controller, wherein the birefringence material is disposed on the light modulation element The optical axis of the molecule (M) is a two-dimensionally calibrated, tunable medium that adjusts the calibration of the molecule in one dimension independently of the other. The device of claim 1, wherein the birefringent molecular material consists of a liquid crystal layer (LC). For example, the device of claim 1 is a two-dimensional calibration of molecules through two externally adjustable media. As for the device of claim 3, at least one of the externally acting media is an electric field. As for the device of claim 3, wherein at least one medium acting outside is a magnetic field. The apparatus of claim 1, wherein the calibration of the molecular (M) optical axis is performed on the optical medium in at least one plane. Such as the device of claim 3, in which each of the light modulation elements There are two media of the same type that are perpendicular to each other. The device of claim 6, wherein the birefringent molecular material has a doped dye molecule. The optical modulation device of claim 8, wherein the calibration is performed on a plane by a polarizing mirror of an input end or a polarization direction (PO) of the writing light incident by the linear polarized light source, On the other plane, the electric field is calibrated. The device of claim 6, wherein the device further comprises a photoconductive material layer, wherein the molecular (M) optical axis of the birefringent molecular material is calibrated by a change in intensity of the written light incident on the photoconductive material layer. For example, the device of claim 2 is a spatial light modulation device containing a light modulation element, and a full image of a scene is written therein. The device of claim 11 further includes a lighting unit and an optical system for reproduction of the holographic scene. The device of claim 11, wherein the light modulation element is a pixel (P), and the calibration medium has a pixel configuration. A method of light modulation, which is achieved by a device for modulating amplitude and phase of sufficient coherent light waves through a device having regularly arranged and controllable light modulation elements, wherein the device has a birefringent molecule a controllable layer of material, and a polarizer disposed at the output, wherein the calibration of the optical axis of the birefringent material on the light modulation element is controlled by a modulation controller System, wherein there is an adjustable medium for two-dimensional calibration of the optical axis of the molecule (M) of the birefringent material on the light modulation element, the adjustable medium can adjust the molecule independently of the other dimension in one dimension calibration. For example, in the light modulation method of claim 14, wherein the molecular (M) optical axis is calibrated through an adjustable medium that is independent of each other by external influences. For example, in the light modulation method of claim 14, wherein the molecular (M) optical axis is calibrated in a continuous manner. The light modulation method of claim 15, wherein two mutually perpendicular electric fields on each of the light modulation elements act on the molecular optical axis, and the intensity is adjusted in a mutually independent manner. A method of light modulation according to claim 15 wherein two mutually perpendicular magnetic fields on each of the light modulation elements act on the molecular optical axis and the intensity is adjusted independently of each other. The method of optical modulation according to claim 15, wherein the calibration of the molecular (M) optical axis is performed on the optical medium in at least one plane. The method of optical modulation according to claim 15 wherein the molecule (M) is calibrated in a mutually independent manner by any combination of a magnetic field, an electric field and an optical medium. The optical modulation method of claim 15, wherein the device is a spatial light modulation device of a holographic reproducing device, and the hologram of a scene is written into the optical tone The light modulation element of the variable device. For example, in the optical modulation method of claim 21, one illumination unit illuminates the hologram and cooperates with an optical system to generate a holographic reconstruction image of a scene. The method of optical modulation according to claim 19, wherein the photo-alignment in the birefringent molecular material doped with the dye molecule is on the plane of the spatial light modulation device, and is perpendicular to The optical axis of the molecule is calibrated by an electric field on the plane. For example, in the optical modulation method of claim 19, a polarizing mirror disposed on the light input surface or the light output surface of the optical modulation device will polarize the light wave. The optical modulation method of claim 22 or claim 24, wherein the illumination unit has at least one linearly polarized light source, and the polarization functionalization thereof can replace the polarization mirror disposed on the light input surface. A holographic reproducing apparatus having an illumination unit, a light modulator having a regularly arranged pixel and a liquid crystal layer, and an optical system functioning by being modulated in the optical modulator Light waves reconstruct a three-dimensional scene within a reconstruction range in which the molecules of the liquid crystal layer and their optical axes are phase- and amplitude-modulated for sufficient coherent light waves of a lighting unit through a modulation controller. The two-dimensional calibration is performed on an adjustable medium that affects the pixel, wherein the calibration of the molecule can be adjusted independently of the other dimension in one dimension, wherein the adjustable medium acting on the pixel is according to the first to the first 13 items The method of any of the above is formed so as to be able to simultaneously modulate the final phase value and amplitude value of the holographically encoded three-dimensional scene.